Each of the many ways to answer merci has a specific meaning in French:

De rien (it was nothing)

Service (at your service)

Il n'y a pas de quoi (nothing to worry about)

C'est tout naturel (of course)

C'est un plaisir (my pleasure)

How to formulate an answer along the lines “your thanks are well deserved, because what I did was neither natural nor a pleasure and please notice that I'm not your servant” in a less clumsy and more polite way?